This diagram from a 1967 documentation shows how to switch high voltage neon lamps with 5V TTL outputs. The circuit can be adapted to function as a shield.
We found this circuit in Popular Electronics from 1992. Time is given by C1. The circuit provides an...
A Popular Electronics from the 90's suggests this circuit that is based on a low voltage...
The frequency of a 555 oscillator depends on the capacitance of capacitor C. We can take advantage of...